The present invention relates to nutritional enrichment of foodstuffs such as, but not limited to pork, beef, poultry and the like and more particularly relates to the use of a selection of feed supplements formulated for feeding to animals at predetermined stages of growth and which include increased levels of omega 3 long chain fatty acids. The invention further provides feed formulae for animals at various stages of development and which result in produce having an increased human nutritional quality due to an increased level of long chain omega 3 fatty acids but without taint of the food product. Whilst the supplement and formulae of the present invention are suitable as feed for producing high nutritional quality beef and poultry (in the latter case influencing the nutritional value of poultry meat and eggs) the invention will mainly be described with reference to its application in pig feeding.
It is long established that there is a direct relationship between animal feed and the quality of food produce from a particular animal. An example of this relationship is evident where fish meal is used in pig feeding with the constituent ingredient levels of fish meal impacting on the nutritional quality of the food.
The food industry, in recognition of the desirability of lowering of saturated fats in the human diet has paid particular attention to improvement of the nutritional quality of foodstuffs and this begins with the animal feed blends. For instance, in the last ten years the average fat content of pork has been reduced by more than 50% in direct response to consumer demand for low fat diets in view of the links between high cholesterol, heart disease and a high fat diet. Animal products including pork also contain polyunsaturated fatty acids (PUFA). Pork and animal product producers have in recognition of the high nutritional benefits of long chain omega 3 PUFA and the consequent high consumer demand for foods with high yields of these nutrients have paid particular attention to the sources of these fatty acids and more particularly to ways of fortifying foods with long chain omega 3 PUFA.
Omega 3 polyunsaturated fatty acids, like vitamins, are essential to good health but as the body cannot itself manufacture these essential acids and vitamins it must rely on food sources for the requisite supply of these necessities. Foods rich in long chain omega 3 fatty acids are generally not a regular part of the diet so most people are denied the fill potential benefits of the presence of these in the diet.
Polyunsaturated fats are divided into the omega 3 and omega 6 fatty acids both of which the body needs. The effects of long chain omega 3 fatty acids on the body are significant as they are incorporated into every cell, tissue and organ including the heart and lungs, blood vessels, brain and joints.
There are a variety of food sources of long chain omega 3 fatty acids for example, Alpha-linolenic acid (ALA) occurs in oils such as canola, linseed (flaxseed), walnut and soybean as well as in green vegetables. Eicosapentaenoic acid (EPA) can be found in cod liver oil, fish oils fish and other seafoods and even in beef Docosahexaenoic acid (DMA) is found in tuna oil, other fish oils and in breast milk.
While omega 6 fatty acids are also beneficial and necessary for a good diet, the ratio of omega 6 fatty acids to omega 3 should be less than 5:1 and preferably 1:1. An excess of omega 6 acids can negate the effect of the long chain omega 3 fatty acids. Long chain Omega 3 fatty acids (EPA and DMA) are derived from fish and are more potent than the short chain omega 3 derived from plants (ALA) as they are taken up directly by the cells. The evidence for the health benefits of DMA and EPA in the diet is nowhere better demonstrated than in Japanese fisherman and Eskimos who both have diets high in fish and a low incidence of heart disease. Omega 3 fatty acids also play a role in slowing the build up of fats on the walls of blood vessels, reducing blood clotting, reducing blood pressure and decreasing arythmia. There is also evidence that omega 3 fatty acids can reduce risk of cancer and depression and can strengthen the immune system.
The problem for the food industry has been to determine the most effective means of introducing long chain omega 3 fatty acids into the diet without compromising the physical, textural and sensory quality of the food vehicle. Egg producers introduced long chain omega 3 fatty acids into eggs by feeding hens foods such as fish meal which are high in these acids only to discover that the eggs tasted like fish leading to a reduction in consumption of such fat modified eggs. The hens were then fed a unique vegetarian diet of natural foods that are rich in long chain omega 3 fatty acids but there are significant restrictions on how much fatty acid can be introduced due to the problem of sensory taint. This is also the experience in the pork industry where fish meal has been fed to pigs to increase the level of long chain omega 3 fatty acids in consumers of pork, but the neat has also suffered from fishy taint which significantly reduces the level of omega three fatty acids which can be introduced.
According to conventional wisdom, high intakes by pigs of fishmeal as a source of long chain omega 3 PUFA above relatively low levels of 2-5% of the food vehicle results in pork taint manifested by decrease in oleic acid content, increase in iodine value (hence oxidizability), as well as softening of the carcass fat. Thus there has traditionally in use of PUFA been a necessary compromise between achieving an optimum nutritional value associated with use of PUFA's while guarding against taint from excessive use.
This has kept the use of PUFA's in pig feed to low levels primarily due to the undesirability of taint. The problems of taint and the desirability of increasing the PUFA content in the human diet has been recognised in the industry literature. See for instance the article entitled “Omega 3 Enriched Pork” by Peter R. C. Howe—Department of Biomedical Science, University of Wollongong, NSW, Australia. For an enriched omega 3 product to be regarded as a useful dietary source it should be able to increase the level of omega 3 fatty acids present in the circulation when consumed in reasonable quantities, Although increases have been reported for consumption of omega 3 eggs there has been no similar demonstration of potential benefit to humans with other alternative dietary sources of marine omega 3 fatty acids apart from refined fish oil supplements.
In recognition of the benefits of long chain omega 3 PUFA, the food industry turned its attention to identifying an economic and plentiful source of these acids. Fish oil was considered an obvious source of these fatty acids and experimentation was conducted to determine the levels which could be used in pork recognising that levels above a desirable maximum, could result in taint of the pork.
An industry objective has therefore been to determine the extent of omega 3 PUFA enrichment of animal produce that could be achieved using fish meal without the problems of taint. Experimentation found that only very low percentages 0.8-1.4% of fish oil could be used in the diet and it was found preferable that the use should be terminated or reduced to the lowest levels before slaughter. The experiments demonstrated that increasing fish oil intake increased the percentage of long chain omega 3 PUFA and therefore the nutritional qualities of the produce. It was also found that where diets contained 3% fish oil up to slaughter, the organoleptic quality of the pork was affected. The industry then turned its attention to the use of fish meal as a source of long chain omega 3 PUFA for the enrichment of pork but taint of the physical and sensory qualities of the pork remained a problem. The industry currently recommends that the fish meal content of pig rations not exceed 5% of the total diet and only where the fish meal is withdrawn 5-7 weeks before slaughter. Where the pigs are fed fish meal up to slaughter it is recommended that the level of fish meal in the diet not exceed 3%. The conventional source of fish meal is pelagic fish, which when rendered into meal, normally has an oil content of 6%-9%.
The applicant has for some time (in order to meet the challenge of elimination of taint) been involved in experimentation to determine fish meal formulae for feeding to animals [depending upon the stage of development of the animal to which the food blend is fed] to optimise the retention of omega 3 long chain PUFA but without taint caused by the fish meal through off flavours and rancidity of the produce.
Although experts in the field have postulated as to possible ways to increase the use of fish meal without taint of the produce, no one to date has succeeded in increasing the fishmeal level above 3%-5% of the total diet without risk of taint of the produce. Some in the food industry advise against feeding fish meal at any time during the 14 day period before slaughter to eliminate the possibility of taint.
The August 1998 issue of the organ of the Fishmeal Information Network commissioned an independent study by a pig nutritionist to review the available data on use of fish meal in feeding pigs. The study found that fish meal, provided that it does not exceed 10% oil content, can be fed at up to 7.5% of the diet without presenting any problems of taint in the end product. The findings do however recognise that for 100% security against taint, percentage levels of fish meal in the diet should be set below 7%. Thus it is generally recognised in the industry that it is undesirable to increase the percentage of fishmeal beyond 3%-5% percent to be sure of elimination of taint.